Switching devices are typically intended to provide a continuous power supply to a motor or an electrical load and associated circuitry.
Switching devices divert or switch power from its primary/intended electrical power source to a secondary/emergency source of power in the event of loss of primary power.
Overload switching generally occurs when switching power to a motor and almost 6-10 times rated current is observed. After physical separation of the contacts of a switch, high current continues to flow through a channel of hot ionized plasma, namely the arc. An arc erodes the contact material and hence reduces the life of a switch.
The severity of the arc increases with the current level. To reduce erosion and damage to switches, the arc should be quenched very fast. Splitter plates are provided in the arc chamber for this purpose. Splitter plates known in the art have a single center notch. The plates are stacked parallel to each other and vertically in the same plane as the contacts of the switches. To quench the arc, an arc chamber consisting of a stack of splitter plates structured to break up the generated arc is provided. When the movable electrical contact is separated from the fixed contact, an arc is generated and is pulled into the arc chamber due to electromagnetic forces. The arc gets elongated, and then splits into a series of several arcs and the arc voltage starts increasing. When the arc voltage is greater than the system voltage, it leads to arc quenching. Splitter plates also help in cooling of the arc.
Due to cooling, the arc diameter reduces, which in turn increases the arc resistance. This helps in arc extinction.
Conventionally, splitter plates are designed with only one notch at the center. The conventional structure and arrangement of splitter plates is associated with many limitations. One such limitation is the travelling distance of the arc from the electrical contacts to the center notch, which is very large. Due to the large travelling distance, arcing time increases which subsequently increase erosion of the tips of the electrical contacts. Due to increased arcing time, the thermal stress on the arc chamber and the entire switch also increases. The magnetic material of the splitter plates in the vicinity of the arc chamber is also less due to which electromagnetic force exerted on the arc is less, which is a highly unfavorable condition for extinguishing the arc.
Therefore, there is felt a need to provide an efficient and improved splitter plate to reduce total arcing time by increasing electromagnetic attractive forces, thereby improving electrical life of a switching device.